This converts a Chefman 5-Tray Food Dehydrator into a filament dryer.
I chose this model because it is compact, simple, and relatively inexpensive.
It will hold a spool up to 13cm wide with a diameter of up to 23cm. It can handle multiple spools by simply printing more and stacking them.
The model is one half and is meant to be printed as a pair and glued together. I chose a glue joint to keep the seams small and unobtrusive.
I recommend drying it in-place with a spool to both dry the filament, and the glue in one shot.
Picture shows a 1kg spool of Prusa Orange PETG inside.
Note that this barely fits on a Prusa bed. Take care to exactly center the pair on the Y axis, especially if you use any perimeters.